1. Field of the Invention
This invention relates to a rotor which is suitable for use in making a printed motor having a small size and a flat shape and therefore a wide scope of applicability.
2. Description of the Prior Art
A printed motor is widely used, since it can be installed in a narrow space because of its small size and flat shape and yet can produce a large output. The steps of manufacturing a typical known printed motor are shown in FIGS. 3 and 4 of the accompanying drawings. A multiplicity of radially extending narrow slots 2 so shaped as to define parts of a coil are made in a thin steel sheet 1 to form a sheet coil 4 composed of a multiplicity of radially extending coil segments 3, as shown in FIG. 3. Two such sheet coils 4 are bonded together back to back with an insulating sheet 5 interposed therebetween, the central portion of the bonded assembly is cut away along a circular edge, and the inner ends of every pair of coil segments 3 facing each other are welded together as shown at 6 in FIG. 4. Then, the coils are bonded together with a similar insulating sheet 7 interposed therebetween, the outer portion of the bonded assembly is cut away along a circular edge beyond the coil segments 3, and the outer ends of every pair of coil segments 3 facing each other are welded together as shown at 8 in FIG. 4, whereby an armature 9 is formed. A hub is fitted in the center of the armature 9 with a similar insulating sheet interposed therebetween, and a rotating shaft is fitted to the hub, whereby a flat rotor is obtained.
It has, however, been usual to use glass fabrics impregnated with an epoxy resin as the insulating sheets. It has, therefore, been very likely that the deterioration of the resin may cause the rotor to be mechanically or electrically damaged when the printed motor is used at a high temperature. No measure has been taken to make a printed motor which can withstand use at a high temperature.
It is necessary to use insulating sheets having high resistance to heat to make a printed motor which can be used at a high temperature, or to which a large amount of electric current can be supplied. The known rotor has, however, the drawback that the resin which the insulating sheets contain is easily deteriorated by heat when the motor is used at a high temperature. The deterioration of the resin results in mechanical damage between the armature and the hub, or electrical damage, such as shortcircuiting between the upper and lower sheet coils. Therefore, the printed motor having the insulating sheets as hereinabove described in its rotor is incapable of use at a high temperature.